Airlines cash in when flyers use credit, debit cards

Charging for services that used to be free is more than a fashion: it has become essential to the profitability of airlines, an industry that has spent much of the past decade racking up large losses.

But, if so-called ancillary revenue is now the financial salvation of airlines, regulators have also begun pushing back, in particular against those that impose large surcharges for financial transactions that cost a few cents to complete.